Little Colorado spinedace description

A small fish in the Cyprinidae family (4), the Little Colorado spinedace (Lepidomeda vittata) belongs to a unique group of fish that are endemic to the lower and middle Colorado River basin in the south-western United States (5). The Little Colorado spinedace has distinctive large round eyes and a rounded snout. It has a slightly slanted mouth and, like other cyprinid fish, lacks teeth in its jaw, instead having two rows of enlarged bones in the throat known as ‘pharyngeal teeth’ (3).

The sides of the Little Colorado spinedace are silvery (3), often with darker silver lines that run vertically down the sides of the body (2). Occasionally it may have blotches (3) or dark, pepper-like markings (2), though these are generally rare (3). This species is typically darker above (3), with the upperparts usually appearing olive, blue or grey (2). The underside of the body is generally white (3), although parts of the belly may sometimes appear a pale, watery yellow (2).

A conspicuous cream-coloured spot is positioned close to the dorsal fin(2), which is relatively large and fairly pointed (3). The fins of the Little Colorado spinedace are largely clear; however, in male fish, the base of the pectoral and pelvic fins may turn an intense reddish-orange, while in females they are usually watery yellow or reddish-orange. Tubercles may sometimes be present on the body of the male (2).

Related species

Little Colorado spinedace biology

A fairly opportunistic feeder, the Little Colorado spinedace is known to prey primarily on the adult and larval stages of terrestrial and aquatic insects, as well as green algae and crustaceans in the summer months. Terrestrial insects form the main component of the diet during the summer and autumn, whereas aquatic insects are more important during the winter (4). This species will also eat small fish and may even exhibit some cannibalistic behaviour, preying on juveniles of its own species that are less than two centimetres in length (3)(4).

The peak breeding season of the Little Colorado spinedace is between May and June, although this species does spawn sporadically throughout the summer and early autumn (3). During courtship, the male Little Colorado spinedace will follow the female, nibbling at the female’s body (2). The fish will make small depressions in the gravel at spawning sites, in which the female lays a clutch of eggs (3). It is thought that between four and eight males may attend each spawning female (2). Eggs may also be randomly deposited over the stream bottom, on aquatic vegetation or on debris, typically in areas of slow-flowing water (2). The eggs of the Little Colorado spinedace are left to develop unattended and receive no parental care (3).

Little Colorado spinedace range

The Little Colorado spinedace has a restricted range and is found only in a small area of the United States (5), occurring mainly in the Little Colorado River and its north-flowing tributaries (1).

Historically, the Little Colorado spinedace is thought to have had a much larger range, having previously also occurred throughout the upper sections of the Little Colorado River system in eastern Arizona (1). It is thought that this species may also have originally inhabited suitable waters in western New Mexico (2)(3)(5).

Species with a similar range

Little Colorado spinedace habitat

Capable of occurring in relatively harsh environments (3), the Little Colorado spinedace prefers to inhabit rocky or sandy habitats in small freshwater pools, creeks and rivers which are less than 1.5 metres deep (1)(3).

This species is most common in areas with a fine gravel substrate, where the water current is slow to moderate and the water temperature is between 14 and 26 degrees Celsius (1)(3). It can be found in both clear and turbid waters, and generally prefers pools with little shade and where the flow of water has caused the bank to become cut away beneath the surface (1).

The Little Colorado spinedace will retreat to small springs and pools in streambeds during dry periods (1).

Little Colorado spinedace status

Little Colorado spinedace threats

Habitat loss is considered to be the primary threat to the survival of the Little Colorado spinedace, largely due to the construction of dams and roads, as well as water extraction and the channelling of streams away from their original course (1)(2).

The introduction of crayfish and other non-native species, such as the rainbow trout (Oncorhynchus mykiss) and the green sunfish (Lepomis cyanellus), has also led to the decrease in populations of the Little Colorado spinedace, as these species compete for resources and predate upon the spinedace (1)(2).

Long-term drought has also limited the amount of water available to the Little Colorado spinedace throughout its range, and this may be further exacerbated in the future by the potential impacts of climate change (1).

Little Colorado spinedace conservation

Much of the Little Colorado spindedace’s habitat is under federal ownership, and in an effort combat its population decline, the waters of East Clear, Chevelon and Nutrioso creeks have been designated as ‘Critical Habitat’ for this species. The remaining areas inhabited by the Little Colorado spinedace are either managed or owned by the U.S. Forest Service, the Arizona Game and Fish Department and the Bureau of Indian Affairs, as well as private landowners (1).

There is a need for future management efforts to be directed towards conserving all existing populations of the Little Colorado Spinedace, as well as all areas of remaining habitat (1). Additional recommended conservation measures include potentially reintroducing this species into areas it has previously inhabited (3), as well as reducing the impact that non-native fish have on populations of the Little Colorado spinedace (1)(3).

A recovery plan has been established for the Little Colorado spinedace, which aims to identify the necessary steps to protect and restore existing spinedace populations, re-establish extirpated populations, and protect and enhance existing habitats for this threatened fish (2).

Glossary

Algae

Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.

Crustaceans

Diverse group of animals with jointed limbs and a hard external skeleton, characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.

Dorsal fin

The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans (whales, dolphins and porpoises).

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Larvae

The stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Pectoral fins

In fish, the pair of fins that are found on either side of the body just behind the gills. They are generally used for balancing and braking.

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